Maternal pinealectomy alters the daily pattern of fetal breathing in sheep.
We have investigated the effect of pinealectomy of the pregnant ewe on the 24-h pattern of fetal breathing activity during late gestation. Fetal breathing movements were recorded during 24-h periods on 18 occasions in 5 pinealectomized ewes and on 24 occasions in 6 pineal-intact ewes between 120 and 145 days gestation. All ewes were fed once daily between 1000 and 1300 h and were kept under a light-dark cycle 12:12 h. There was no significant difference in the mean hourly incidence of fetal breathing movements between the pineal-intact (27.2 +/- 0.5 min/h) and pinealectomized (25.5 +/- 0.6 min/h) groups. However, there was a significant difference in the 24-h profiles of fetal breathing movements in the two groups. The peak incidence of fetal breathing occurred between 1900 and 2000 h in the pineal-intact ewes and between 1200 and 1300 h in the pinealectomized ewes. We conclude that maternal pinealectomy alters the daily pattern of a fetal behavioral pattern and that maternal melatonin may therefore provide the fetus with information about time of day.
McMillen
I C
IC
Department of Physiology, Monash University, Clayton, Victoria, Australia.
Nowak
R
R
Walker
D W
DW
Young
I R
IR
D000818:Animals; D002940:Circadian Rhythm; D005260:Female; D005324:Fetal Movement; D005333:Fetus / Q000502:physiology*; D008431:Maternal-Fetal Exchange; D010870:Pineal Gland / Q000502:physiology* / Q000601:surgery; D011247:Pregnancy; D012119:Respiration / Q000502:physiology*; D012756:Sheep